Hi @Yoav Crombie,

See here on my blog

https://microsoft365pro.co.uk/2019/09/16/teams-real-simple-with-pictures-applying-data-loss-preventi...

Note: As outlined here on Petri, Teams communications are internal whilst DLP checking for other workloads focuses on outbound email/document sharing. The DLP policy must therefore cover content shared “only with people in my organization” (many existing policies are likely set to cover content shared “with people outside my organization.” In the context of Teams, this means teams with guest users). It is recommended – if external and guest access is on to set two DLP Policies – one internal and one external.

Hope that answers your question!

Best, Chris